Development of sodium alginate–aloe vera hydrogel films enriched with organic fibers: study of the physical, mechanical, and barrier properties for food-packaging applications

Hydrogels from a botanical origin can be beneficially utilized in the development of edible and biodegradable food-packaging films. Polymer hydrogels are biodegradable and non-toxic in nature and have the potential to replace conventional plastics. In the present study, composite films based on alginate and aloe vera were reinforced with two hydrogel-forming polymers, namely gum tragacanth (GT) and hydroxypropyl methylcellulose (HPMC). A comparative study to assess their reinforcing effect in improving the physical properties as well as mechanical properties of the films was carried out. It was observed that both GT and HPMC significantly improved the tensile strength (TS) of the composite films whereby the TS increased to a maximum value of 68.25 MPa at a 12% concentration of GT and 52.19 MPa at a 4% concentration of HPMC. The flexibility of the films was also improved by incorporating the two hydrogel-forming polymers that caused an increase in the thickness, moisture content, swelling index, and water vapor permeability (WVP) of the composite films. However, the oxygen permeability (OP) was reduced by the addition of GT and the value decreased from 1.46 × 10−15 to 0.45 × 10−15 g m−1 s−1 Pa−1 at the maximum concentration of GT. The solubility of the films also decreased as a result of adding GT and was reduced to 23.12% at a 14% concentration of GT.